Predicting full-thickness necrosis in adult acute corrosive ingestion injuries in a sub-Saharan African setting

Abstract

BACKGROUND

Corrosive ingestion remains an important global pathology with high morbidity and mortality. Data on the acute management of adult corrosive injuries from sub-Saharan Africa is scarce, with international investigative algorithms, relying heavily on computed tomography (CT), having limited availability in this setting.

AIM

To investigate the corrosive injury spectrum in a low-resource setting and the applicability of parameters for predicting full-thickness (FT) necrosis and mortality.

METHODS

A retrospective analysis of a prospective corrosive injury registry (March 1, 2017–October 31, 2023) was performed to include all adult patients with acute corrosive ingestion managed at a single, academic referral centre in Cape Town, South Africa. Patient demographics, corrosive ingestion details, initial investigations, management, and short-term outcomes were described using descriptive statistics while multivariate analysis with receiver operator characteristic area under the curve graphs (ROC AUC) were used to identify factors predictive of FT necrosis and 30-day mortality.

RESULTS

One-hundred patients were included, with a mean age of 32 years (SD: 11.2 years) and a male predominance (65.0%). The majority (73.0%) were intentional suicide attempts. Endoscopy on admission was the most frequent initial investigation performed (95 patients), while only 17 were assessed with CT. Seventeen patients had full thickness necrosis at surgery, of which eleven underwent emergency resection and six were palliated. Thirty-day morbidity and mortality were 27.0% and 14.0%, respectively. Patients with full thickness necrosis and those with an established perforation had a 30-day mortality of 58.8% and 91.0%, respectively. Full thickness necrosis was associated with a cumulative 2-year survival of only 17.6%. Multivariate analyses with ROC AUC showed admission endoscopy findings, CT findings, and blood gas findings (pH, base excess, lactate), to all have significant predictive value for full thickness necrosis, with endoscopy proving to have the best predictive value (AUC 0.850). CT and endoscopy findings were the only factors predictive of early mortality, with CT performing better than endoscopy (AUC 0.798 vs 0.759).

CONCLUSION

Intentional corrosive injuries result in devastating morbidity and mortality. Locally, early endoscopy remains the mainstay of severity assessment, but referral for CT imaging should be considered especially when blood gas findings are abnormal.

Key Words: Corrosive injuries; Caustic injuries; Adult; Predicting necrosis; Endoscopy predictive performance; CT predictive performance; Short-term survival

Core Tip: Management of acute adult corrosive injuries remains internationally under-reported, but specifically in sub-Saharan Africa. This large series of 100 patients highlights the high rates of morbidity and mortality, especially when full thickness necrosis is established. Predicting necrosis on admission is challenging, with international guidelines proposing computed tomography (CT) as the investigation of choice. With limited availability of CT, endoscopy still performs well in our setting. CT should be considered in patients with suspected severe corrosive injury with abnormal findings on blood gas (pH, base excess, and lactate) serving as accurate and practical markers of severity in a low-resource setting.

INTRODUCTION

Corrosive ingestion injuries remain a global problem with significant rates of associated morbidity and mortality[1]. A bimodal distribution, which includes paediatric injuries (which are mostly accidental) and adult injuries (which are mostly intentional) result in injuries of differing severity[2]. Management focuses on both the acute emergency management of these injuries, but equally on the long-term sequelae in those surviving the acute period, with oesophageal strictures being the most frequent chronic complication. The most concerning acute complication remains full thickness foregut necrosis with perforation resulting in significant mortality[1]. Outcomes may be improved with early identification of full thickness necrosis allowing for timeous surgical resection of any necrotic organs, prior to perforation occurring. Early endoscopic assessment using the Zargar classification[3], has been the cornerstone of severity assessment for over three decades, but has been replaced in most contemporary centres by computed tomography (CT) grading[4,5]. CT grading out-performs endoscopy in selecting patients for acute resection, as the axial imaging allows for more accurate assessment of necrosis depth, compared to the purely luminal assessment of endoscopy[4,5]. International data also suggest that serum blood tests, including raised white cell count, C-reactive protein, acidosis (with high lactate and low pH), deranged liver function tests and low platelet count, may aid in identifying full thickness necrosis[1].

Data on corrosive injuries from sub-Saharan Africa (SSA) is limited and focuses predominantly on the management of paediatric injuries and chronic oesophageal strictures[6-12]. Management of acute adult injuries is almost completely undescribed in SSA, but one recent cohort highlights the significant challenges these injuries pose in a low resource setting, with a predominantly young, male demographic with intentional ingestion and limited use of CT imaging for acute assessment[13].

This study was performed to review the severity, management, and outcomes of acute corrosive ingestion injuries in a low resource SSA setting and to identify predictive factors of full thickness necrosis and short-term mortality.

MATERIALS AND METHODS

All adult patients managed for corrosive ingestion-related gastrointestinal injuries at Groote Schuur Hospital by the Upper Gastrointestinal Surgery Unit between March 1, 2017–October 31, 2023 were analysed for inclusion. Exclusions included patients managed during this period for only the chronic sequelae of corrosive ingestion and those where acute management data was lacking (e.g. managed initially at another institution). Data were retrospectively analysed from an ethically approved prospectively maintained corrosive injury registry (HREC REF: R009/2022) with study approval by the University of Cape Town Human Research Ethics Committee (HREC REF: 347/2022)

All patients presenting after an acute corrosive ingestion are assessed and managed as per the Advanced Trauma Life Support principles[14]. Assessment of injury severity is by either endoscopy or computed tomography (this is decided by imaging availability and by the initial treating physician). Early contrast swallow assessments are not advocated in our service. Patients with suspected full thickness necrosis are expedited to theatre for operative assessment.

Groote Schuur Hospital is one of two tertiary academic referral centres for several public regional hospitals in the Western Cape province, which has an estimated population of over 7 million[15]. The hospital also accepts self-referred patients who live within the surrounding suburbs of the hospitals. CT imaging facilities are available 24 hours a day at Groote Schuur Hospital but not at all the referring hospitals, while upper gastrointestinal endoscopy is generally available 24 hours a day at most referring centres.

Definitions

The main outcomes analysed were 30-day mortality and morbidity (i.e. 30 days from the corrosive ingestion incident).

Endoscopic and CT severity grading

Endoscopic grading of acute corrosive injuries was performed using the modified Zargar classification[16]. CT grading was performed according to the CT grading published by Chirica et al[1] (Table 1).

Table 1 Classification systems for endoscopic and computed tomography grading of acute corrosive injuries.

Modified Zargar endoscopic grading[1]
Grade 0	Normal
Grade I	Oedema and hyperaemia of mucosa
Grade IIA	Superficial localised ulcerations, friability and blisters
Grade IIB	Circumferential and deep ulcerations
Grade IIIA	Multiple and deep ulcerations and small, scattered areas of necrosis
Grade IIIB	Extensive necrosis
Grade IV	Perforation
CT grading[2]
Grade 1	Normal appearance
Grade 2	Wall and soft tissue oedema, increased wall enhancement
Grade 3	Transmural necrosis with absent wall enhancement (with or without perforation)

Statistical analysis

Data analysis was performed using Microsoft Excel and IBM SPSS Statistics (version 29.0.0.0). Patient demographics, corrosive ingestion details, initial investigations, management, and short-term outcomes were described using simple descriptive statistics, with mean ± SD for parametric data and median with inter-quartile range for non-parametric data. Survival data of those patients with full thickness necrosis and those without were compared and presented using Kaplan-Meier curves. Multivariate analysis was performed to assess for any factors associated with full thickness necrosis and 30-day mortality using the Chi-squared test for univariate categorical data and Kruskal-Wallis test to allow for comparison of multiple groups with non-parametric data. Furthermore, post-hoc multiple comparison analyses using the Mann-Whitney U test were performed on any variables shown to be statistically significant. Performance of endoscopy, CT grading and blood gas parameters (pH, base excess, and lactate) were further analysed to assess specificity, sensitivity, and positive and negative predictive values for full thickness necrosis prediction. A P value of < 0.05 was considered statistically significant. Factors found to be statistically significantly associated with the tested outcome (necrosis or mortality) were then tested for predictive performance using the area under the curve (AUC) of receiver operator characteristic (ROC) curves. An AUC value of 0.700–0.800 was considered acceptable, while a value > 0.800 was considered excellent for predictive performance.

RESULTS

During the 80-month study period a total of 126 patients with corrosive ingestion-related injuries were treated, of which 100 patients met the inclusion criteria. The mean age was 32 years (SD: 11.2 years) with most being male (65.0%). Two-thirds had no known medical comorbidities, with 15% known with a prior psychiatric history. Forty-one patients reported substance use of which cigarette smoking was the most common (31.0%). Eleven patients had a prior suicide attempt, of which one was a corrosive ingestion and the others combinations of polypharmacy overdose, hanging and other unknown mechanisms. No patient in the study cohort was known with a prior accidental corrosive ingestion. Table 2 outlines patient demographics at baseline.

Table 2 Baseline demographics and details of the corrosive ingestion incident.

Baseline demographics (n = 100)	n	%
Gender
Female	35	35.0
Male	65	65.0
Comorbidities
No	67	67.0
Yes	33	33.0
Specified comorbidities
Known psychiatric history	15	15.0
HIV positive	12	12.0
Hypertension	2	2.0
Obesity	3	3.0
Diabetes mellitus	1	1.0
Other comorbidity	7	7.0
Substance use
No	59	59.0
Yes	41	41.0
Substance use specified
Smoking	31	31.0
Alcohol - regular use	21	21.0
Marijuana	10	10.0
Methamphetamine	8	8.0
Methaqualone	7	7.0
Opioids	1	1.0
Prior corrosive ingestion/suicide attempt
Yes	11	11.0
No	89	89.0
Corrosive ingestion incident (n = 100)
Intentional/accidental
Intentional (suicidal)	73	73.0
Accidental	20	20.0
Forced ingestion (assault)	5	5.0
Unknown	2	2.0
Substance ingested
Acid	32	32.0
Sulphuric acid	22
Hydrochloric acid	3
Other acid	7
Alkali	58	58.0
Sodium hypochlorite (bleach)	30
Sodium hydroxide	27
Other alkali	3
Other corrosive substance	10	10.0
Unknown corrosive substance	5	5.0

HIV: Human immunodeficiency virus.

Most of the ingested substances were alkaline solutions, with bleach (30%) being the most common (Table 3). Almost three quarters (73%) of patients ingested the corrosive in a suicide attempt, 20% were accidental ingestions while five patients were forced to drink corrosive ingestions during assaults. In 20 patients additional non-corrosive substances were ingested, which included toxins in 13 patients, painkillers, and medication in five patients, washing powder, and a non-corrosive cleaning agent. Ingested toxins included alcohol, rat poison, mercury, and organophosphate.

Table 3 Imaging and endoscopy investigations performed on admission.

Imaging/endoscopy during acute admission (n = 100)	n	%	n	%	n	%
Endoscopy	95	95.0
Chest X-ray	82	82.0
Lateral neck X-ray	31	31.0
CT	17	17.0
Contrast swallow	1	1.0
None	1	1.0
Endoscopy findings (n = 95)	n	%	n	%	n	%
	Oesophagus		Stomach		Duodenum
Not entered	1	1.1	3	3.2	32	33.7
Zargar 0	23	24.2	14	14.7	42	44.2
Zargar I	11	11.6	25	26.3	9	9.5
Zargar IIA	20	21.1	14	14.7	7	7.4
Zargar IIB	26	27.4	8	8.4	1	1.1
Zargar IIIA	6	6.3	16	16.8	1	1.1
Zargar IIIB	8	8.4	14	14.7	3	3.2
Zargar IV	0	0.0	1	1.1	0	0.0
CT findings (n = 17)	n	%	n	%
	Oesophagus		Stomach
Grade 1 - normal	2	11.8	5	29.4
Grade 2 - oedematous only	11	64.7	8	47.1
Grade 3 - lack of contrast enhancement
Without perforation	3	17.6	2	11.8
With perforation	1	5.9	2	11.8

CT: Computed tomography.

Early endoscopy was the most prevalent investigation performed with 95 patients assessed at a median time of 24 (IQR 15-40) hours post ingestion. In 7 patients (7.4%) the initial endoscopy was performed more than 72 hours post corrosive ingestion. There were no documented perforations occurring during endoscopy in our cohort. Only 17 patients were assessed using CT, of which 14 also had an endoscopy. In only three patients was the injury severity assessed on CT findings only. A chest X-ray (CXR) was performed on admission in 82 patients with 78 (95.1%) being normal and the other four showing non-specific lung changes. No CXR showed features confirming a perforation and no CXR directly influenced the acute corrosive management. Only one patient underwent a contrast swallow study as part of the acute severity assessment, which was reported as normal.

Twenty-three patients (23.0%) required emergency resuscitation on initial presentation, nineteen of whom necessitated endotracheal intubation for a threatened airway (Table 4). Initial management prior to referral included prophylactic antibiotics in 7.0%, activated charcoal in four patients (of which only one had an actual concomitant toxin overdose warranting the use of activated charcoal). No patient was managed with a pH neutralizing agent. One-fifth (20 patients) required acute surgery, of which 17 were found to have full thickness necrosis. The remaining three patients included two patients needing surgical feeding access (gastrostomy or jejunostomy) and one patient with a negative laparotomy. Eleven underwent an emergency resection, while the remaining six patients had such extensive injuries that an intra-operative decision was made to palliate (Figure 1). Resections performed included oesophagogastrectomy in five patients and total gastrectomy in five. One patient had an oesophagectomy without gastrectomy. In two patients extended resections were performed (additional to gastric or oesophageal resections), which included pancreas-preserving duodenectomy and resection of proximal jejunum in both patients. Nine patients (of the 11 who underwent an acute resection) underwent reconstruction, with three immediate oesophagojejunal anastomoses following total gastrectomy, and six delayed reconstructions. Two resected patients had uncomplicated post-operative courses, while the remaining seven required repeat intervention and/or surgery resulting in major morbidity and/or death.

Figure 1 Flow diagram of patient outcomes. ¹All three patients with minor corrosive injuries on endoscopy but with 30-day mortality died from a concomitant toxin ingestion.

Table 4 Overview of acute management.

Management
Median (IQR) time from ingestion to first healthcare assessment	6 (2-13) hours
Emergency resuscitation	n	%
Required emergency resuscitation	23	23.0
Specified
Endotracheal intubation	19	19.0
Chest compressions	1	1.0
Inotropes	3	3.0
Other1	2	2.0
Other management initiated in the emergency department
Proton pump inhibitor therapy	35	35.0
Prophylactic antibiotics	7	7.0
Therapeutic antibiotics	4	4.0
Nasogastric tube insertion (for drainage, not feeding)	4	4.0
Activated charcoal administration	4	4.0
Steroids	1	1.0
Neutralizing agent	0	0.0
Surgery
Required acute surgery	20	20.0
Decision for needing surgery (n = 20)
Based on endoscopy findings	13	65.0
Based on CT findings	5	25.0
Based on clinical findings only	2	10.0
Type of surgery (n = 20)
Emergency resection performed	11	55.0
Oesophagectomy only	1
Oesophagogastrectomy	5
Gastrectomy only	5
Extended resections2	2
Exploration only - decision for palliation	6	30.0
Feeding jejunostomy (only)	1	5.0
Gastrojejunostomy & gastrostomy	1	5.0
Negative laparotomy	1	5.0

¹Other emergency resuscitation: Atropine with methylene blue administration for bradycardia & methaemoglobinaemia and recurrent emergency potassium shifting for refractory hyperkalaemia.

²Extended resections: Oesophagogastrectomy/total gastrectomy with additional pancreas-preserving duodenectomy and proximal jejunal resection in two patients. CT: Computed tomography.

Thirty-day mortality was 14.0%, with 27.0% having a documented morbidity within 30 days of the corrosive ingestion (Table 5). Nosocomial pneumonia, acute kidney injury and unexpected cardiac arrest were the most common morbidities. One quarter (26.0%) of patients required intensive care admission within 30 days of the corrosive ingestion. Patients found to have full thickness necrosis had a 30-day mortality of 58.8% (including patients selected for palliation) while those who underwent an acute resection had a 30-day mortality of 36.4%. Eleven patients were found to have an already-established perforation at surgery. Of these, 10 (91.0%) died, with the only survivor being a patient who initially had a reassuring CT with modified Zagar grade IIB caustic injury on endoscopy. Following increasing septic markers and pyrexia an oesophagectomy on day 7 after the ingestion was performed for delayed full-thickness perforation, with localized mediastinitis. Patients who underwent an acute resection had a median length of hospital stay for their primary admission of 28 (IQR 19-137.5) days. Kaplan-Meier survival curves show a significant survival difference between those patients with full thickness necrosis and those without. Full thickness necrosis was associated with a cumulative survival of only 17.6% at 2 years (Figure 2).

Figure 2 Kaplan-Meier survival curve comparing cumulative survival in patients with or without full thickness necrosis.

Table 5 Outcomes for 30-days post corrosive ingestion. Acute admission outcomes.

Outcomes (n = 100)	n	%
30-day mortality	14	14.0
30-day morbidity	27	27.0
Required ICU management	26	26.0
Median (IQR) ICU stay	2.5 (2-3.25) days
Median (IQR) length of hospital stay	6 (2-15.5) days
Acute morbidities specified (n = 39)
Pneumonia (nosocomial)	7	17.9
Acute kidney injury	5	12.8
Cardiac arrest (unexpected)	4	10.3
Refeeding syndrome	3	7.7
Systemic sepsis	2	5.1
Unplanned extubation	2	5.1
Surgical site infection	2	5.1
Other	14	35.9

ICU: Intensive care unit.

Multivariate analysis with ROC AUC as predictive of necrosis and mortality, showed that Zargar IIIB findings, grade 3 CT findings, pH, base excess, and lactate to all have good predictive performance for full thickness necrosis, with endoscopy proving to have the best predictive performance (AUC 0.850) (Table 6). CT and endoscopy findings were the only factors predictive of short-term mortality, with CT performing better than endoscopy (AUC 0.798 vs 0.759). Blood gas parameters (pH, base excess and lactate) were further analysed in the whole cohort, but also separately in patients without concomitant toxin ingestion (where blood gas findings may be falsely abnormal due to the toxin and not the corrosive substance). After excluding patients with additional toxin ingestion, both pH and base excess had a 100% negative predictive value for full thickness necrosis. In addition, an abnormal base excess (< 2 mEq/L) had excellent predictive value for full thickness necrosis with a ROC AUC of 0.821 (Table 7).

Table 6 Multivariate analysis of numerous admission variables in predicting full thickness necrosis and short-term mortality, n (%).

Variables			Predicting full thickness necrosis						Predicting acute mortality
		Total, n	No FT necrosis		FT necrosis		P value	ROC AUC	No mortality		Mortality		P value	ROC AUC
Gender	Female	35	31	88.6	4	11.4	0.279		28	80.0	7	20.0	0.207
	Male	65	52	80	13	20			58	89.2	7	10.8
At least one comorbidity	No	67	58	86.6	9	13.4	0.178		56	83.6	11	16.4	0.323
	Yes	33	25	75.8	8	24.2			30	90.9	3	9.1
Known psychiatric history	No	85	71	83.5	14	16.5	0.739		72	84.7	13	15.3	0.377
	Yes	15	12	80	3	20			14	93.3	1	6.7
Known HIV positive	No	88	75	85.2	13	14.8	0.11		74	84.1	14	15.9	0.138
	Yes	12	8	66.7	4	33.3			12	100.0	0	0.0
Prior corrosive/suicide attempt	No	89	75	84.3	14	15.7	0.339		77	86.5	12	13.5	0.673
	Yes	11	8	72.7	3	27.3			9	81.8	2	18.2
Needing endotracheal intubation	No	82	71	86.6	11	13.4	0.043	0.604	69	84.1	13	15.9	0.257
	Yes	18	12	66.7	6	33.3			17	94.4	1	5.6
Needing chest compressions	No	99	83	83.8	16	16.2	0.027	0.529	85	85.9	14	14.1	0.687
	Yes	1	0	0	1	100			1	100.0	0	0.0
Needing inotropes/vasopressors	No	97	81	83.5	16	16.5	0.447		83	85.6	14	14.4	0.480
	Yes	3	2	66.7	1	33.3			3	100.0	0	0.0
≥ Zargar IIIB endoscopic findings	No	79	75	94.9	4	5.1	< 0.001	0.85	74	93.7	5	6.3	< 0.001	0.759
	Yes	16	4	25	12	75			8	50.0	8	50.0
Grade 3 CT Findings	No	12	10	83.3	2	16.7	0.016	0.788	11	91.7	1	8.3	0.026	0.798
	Yes	5	1	20	4	80			2	40.0	3	60.0
Age (years)		100	31 (24-38)		39 (30-50)		0.015	0.687	32 (24-40)		31 (25-40)		0.917
Systolic BP (mmHg)		48	134 (114-143)		129 (113-149)		0.926		130 (113-144)		134 (120-137)		0.919
Diastolic BP (mmHg)		48	80 (73-90)		83 (75-97)		0.309		82 (73-90)		79 (64-91)		0.520
Heart rate (beats per minute)		48	94 (79-109)		86 (72-105)		0.405		93 (76-110)		94 (82-107)		0.965
Urea (mmol/L)		79	4.6 (3.3-5.9)		5.1 (2.7-7.1)		0.686		4.7 (3.2-6.5)		3.9 (3.4-5.4)		0.432
Creatinine (umol/L)		88	70 (57-81)		84 (68-102)		0.038	0.666	72 (58-85)		72 (66-84)		0.892
WCC (× 109/L)		85	14.07 (9.58-18.31)		13.80 (9.76-19.16)		0.695		13.79 (9.59-18.31)		15.75 (10.63-20.50)		0.605
Platelets (× 109/L)		81	253 (210-326)		206 (171-266)		0.045	0.666	245 (194-308)		263 (232-375)		0.142
Calcium (mmol/L)		12	2.21 (2.00-2.35)		1.99 (199-1.99)		0.31		2.15 (1.99-2.35)		2.21 (2.21-2.21)		0.885
pH		41	7.37 (7.31-7.42)		7.13 (7.07-7.35)		0.003	0.823	7.35 (7.17-7.40)		7.36 (7.27-7.43)		0.593
Base excess (mEq/L)		40	-0.50 (-5.50-2.10)		-14.20 (-17.00 to -4.60)		0.004	0.819	-3.2 (-12.1-0.65)		2.45 (-0.58-5.38)		0.020	0.199
Lactate (mmol/L)		40	1.80 (1.20-3.30)		3.20 (2.60-4.45)		0.026	0.746	2.45 (1.20-3.55)		1.55 (1.18-3.48)		0.677
Ingestion to first assessment (hours)		94	6.0 (2.5-14.5)		4.0 (2.0-8.5)		0.209		6.0 (3.0-15.5)		3.0 (1.5-6.5)		0.052

All numerical values expressed as median (inter-quartile range).

FT necrosis: Full thickness necrosis; ROC AUC: Receiver operator characteristic curve area under the curve; HIV: Human immunodefiency virus; CT: Computed tomography; BP: Blood pressure; WCC: White cell count.

Table 7 Admission endoscopy, computed tomography and blood gas performance in predicting full thickness necrosis.

	Total	FT necrosis	Not FT necrosis	Sensitivity, %	Specificity, %	PPV, %	NPV, %	P value	ROC AUC
Endoscopy performance (n = 95)
Zargar IIIB	16	12	4	75.0	94.9	75.0	94.5	< 0.001	0.850
CT performance (n = 17)
CT grade 3	5	4	1	66.7	90.9	80.0	83.3	0.026	0.788
Blood gas performance (n = 40)
pH < 7.35	20	7	13	77.8	58.1	35.0	90.0	0.062	0.679
BE < -2 mEq/L	18	7	11	77.8	64.5	38.9	90.9	0.027	0.711
Lactate > 2.0 mmol/L	21	8	13	88.9	58.1	38.1	94.7	0.014	0.735
Blood gas performance (Patients with concomitant toxin ingestion removed) (n = 35)
pH < 7.35	19	7	12	77.8	58.1	35.0	100.0	0.007	0.786
BE < -2 mEq/L	17	7	10	77.8	58.1	35.0	100.0	0.003	0.821
Lactate > 2.0 mmol/L	18	6	12	77.8	58.1	35.0	94.1	0.046	0.714

FT necrosis: Full thickness necrosis; PPV: Positive predictive value; NPV: Negative predictive value; ROC AUC: Receiver operator characteristic area under the curve; CT: Computed tomography.

DISCUSSION

Corrosive ingestion injuries remain a difficult clinical problem in our setting. Demographics in this series closely resemble those reported by Mthethwa et al[13] also from South Africa, with a low mean age and significant male predominance. Case series from Europe (United Kingdom and France) show a different demographic with a median age approximately 10 years older than in the South African setting and a more equal gender distribution[2,5,17]. As seen in most studies on adult corrosive injuries, intentional suicide attempts remain the most common reason for the ingestion. The majority of patients in this series were not known with a prior psychiatric history, unlike results from international series, such as Challine et al[17] who reported 71.8% of patients having been known with a prior psychiatric history. Five patients in our series were forced to drink a corrosive substance as part of an assault, one of which resulted in severe corrosive pneumonitis and the need for extracorporeal membrane oxygenation. Corrosive assault is not well described and probably reflective of the high rates of interpersonal violence in South Africa which in general also occurs predominantly in young males[18].

Decision-making in the emergency setting revolves around the need for surgical resection. Patient selection is crucial and remains difficult. Delays to resection result in significantly worse outcomes, while unnecessary resections, especially oesophagectomy, carry a significant morbidity and even mortality. CT is now considered in many centres, and by international guidelines, to be superior in selecting patients for resection[1,4,19-21]. Some centres now rely on CT grading only in the emergency setting with endoscopy considered obsolete[5]. Management of severe corrosive injuries may require extended foregut resections and in patients with staged procedures technically demanding delayed reconstructions with high complication rates and poor eventual quality of life[1]. Improving outcomes in these patients is best achieved by management in centralised high-volume centres with access to not only surgery but also minimally invasive interventions[2,17].

CT utilisation in our study, as well as the study by Mthethwa et al[13], was low. This is likely due to a combination of lack of emergency 24-hour access to CT imaging, but also a lack of awareness of the usefulness of CT grading for acute corrosives. It is not clear how many acute corrosive injures were seen within the drainage area during the study period in total, as minor cases have been managed at peripheral hospitals and are not included in this study. Most of these hospitals have 24-hour access to endoscopy but not CT imaging. Non-selective referrals of all corrosive ingestion patients will result in significant strain to an already overburdened tertiary facility. Selective referral of patients with suspected full thickness necrosis is crucial and should be expedited to allow resection before foregut perforation occurs. Perforation prior to surgery in our setting is invariably fatal.

Although plain radiography (CXR or lateral neck X-rays) and basic admission blood tests (full blood count and renal function with electrolytes) are routinely performed the results are of limited value in the acute management. Blood gas parameters (pH, base excess, and serum lactate) were the most useful blood tests to predict necrosis while endoscopy and CT both performed well as imaging modalities. Locally, a blood gas (which is relatively cheap, easy to perform and readily available at almost all emergency centres) can aid in selecting patients for referral for CT assessment.

Although not used for the acute injury severity assessment in some international centres, we still consider endoscopy to be a very useful investigation (especially in patients without necrosis). We recommend that early endoscopy should be considered in all patients who do not have evidence of full thickness necrosis on CT. It must be highlighted that initial reassuring CT and endoscopic findings in severe corrosive cases do not replace close clinical observation, as delayed perforation can still occur, as was evident in one patient in our series who had an oesophageal perforation diagnosed one week after the ingestion incident[22,23].

The limitations of this study include the retrospective nature of the data analysis and the low patient numbers who had CT imaging compared to endoscopy which may have compromised the accuracy of ROC curves and predictive models for CT grading. Lack of data on these injuries in SSA hampers preventive health strategies and even in our setting it is unclear how many of these injuries are seen within the catchment area, but outside of our centre. Further research with multi-centre collaboration would generate larger patient numbers and give a more robust assessment of the full extent of this problem.

CONCLUSION

Acute corrosive ingestion in adults may result in devastating injuries and remains a condition poorly described in SSA. Acute management success hinges on accurate and timeous identification of full thickness necrosis and early surgical resection. CT is the most accurate tool to achieve this, but in resource-constrained environments is not readily available. Endoscopy thus remains an important and invaluable tool. We propose using blood gas findings to select patients who should be acutely referred to an academic centre for emergency CT imaging and assessment for surgical resection.