Amoebic liver abscess: a report from central India

Introduction

Amoebic liver abscess is an important cause of morbidity and mortality in many tropical environments, ours included. Amoebic ‘abscess’ is a misnomer as the fluid consists not of pus, but necrotic liver tissue. Amoebiasis affects approximately 12% of the world’s population at any time ¹ but is endemic in tropical and developing countries where poor sanitation and crowded living conditions exist.^2–4 Transmission of amoebiasis occurs through oral ingestion of cysts in water or food contaminated by faecal matter, use of human excreta as fertiliser and close person-to-person contact.^2–4 The first case was reported by Charles Morehead in 1848. ⁵ The predisposing factors for amoebic liver abscess (ALA) include alcohol ingestion, cirrhosis, individuals with diabetes mellitus and immunodeficiency. Early diagnosis and treatment is necessary to improve the outcome. The diagnosis depends on identification of a fluid collection in the liver, usually by ultrasound, and different treatment modalities (medical management, percutaneous needle aspiration [PNA], percutaneous pigtail catheter drainage [PCD] and interventional surgery) have been described in the literature. In this study we described our experience of amoebic liver abscess.

Materials and Methods

We retrospectively investigated the medical records of 114 patients diagnosed with ALA between January 2012 and September 2014 at the Sri Aurobindo Medical College & P.G. Institute, Indore, India. We collected the detailed clinical, biochemical and radiological data of these patients.

Diagnosis of ALA was based on radiological appearance (ultrasound/computed tomography [CT]), direct visualisation of Entamoeba histolytica trophozoites in pus by microscopic examination, anchovy sauce appearance of pus on gross examination, or positive results of serology for E. histolytica using ELISA technique (DRG International Inc., Springfield, NJ, USA), serum IgG antibodies ≥0.4 OD Units. Alcohol consumption in excess of 60 g per day was considered significant in our study. ⁶

All patients underwent a full blood test, liver and renal function tests, chest radiography, abdominal ultrasound and amoebic serology. All patients were treated with intravenous metronidazole (40 mg/kg/day divided into three doses) and intravenous ceftriaxone 1 g twice daily for 14 days. Inclusion criteria for percutaneous drainage techniques ⁷ (PNA and PCD) were abscess size >5 cm, left lobe abscess, no response to conservative management at the end of 48 h, impending rupture (<1 cm liver tissue between abscess and liver margin). The patients with abscess size in the range of 5–10 cm underwent PNA whereas patients with abscess size >10 cm were considered for PCD. Absence of ascites and normal coagulation profile were prerequisites for percutaneous intervention. The percutaneous procedures were carried out with real-time ultrasound guidance under local anaesthesia (2% lignocaine) with intravenous analgesia and sedation if required. Informed written consent was taken from all patients undergoing percutaneous intervention. Patients with evidence of liver abscess rupture in to the peritoneal cavity were considered for surgical management. All patients were followed up to assess for clinical improvement, length of hospital stay and development of any complications. Periodic sonography was done every third day to assess the cavity size until the patients were discharged. After discharge, all patients were followed up with periodic clinical and ultrasound examination to assess for any symptomatic recurrence and to monitor the size of abscess cavity.

Statistical analysis was performed on SPSS 20.0 (SPSS, Chicago, IL, USA). Comparison of continuous variables was carried out using unpaired student`s t test. Chi-square test was applied to compare between the categorical variable. Statistical tests were based on two-tailed probability. A P value < 0.05 was considered significant.

Results

A total of 114 patients with ALA was studied, and baseline clinical and laboratory parameters are described in Table 1. The male:female ratio was 6.6:1. The mean age of patients was 41.7 ± 13.9 years (range, 18–82 years). Abdominal pain was the most common symptom (92.1%, n = 105) followed by fever (88.6%, n = 101). Tender hepatomegaly and jaundice were present in 78% and 14% of patients, respectively. Alcohol consumption in excess of 60 gm/day (63.2%, n = 72) was identified as a major predisposing factor, followed by diabetes mellitus (11.4%, n = 13). Only one patient was HIV positive.

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Table 1.

Baseline clinical characteristics.

Parameters	n	(%)
Patients, (M/F)	114	(99/15)
Mean age, years (± SD)		41.67 ± 13.86
Fever	101	(88.6%)
Abdominal pain	105	(92.1%)
Diarrhoea	8	(7%)
Nausea	16	(14.03%)
Per rectal bleeding	7	(6.1%)
Vomiting	21	(18.42%)
Hepatomegaly	89	(78%)
Jaundice	16	(14%)
Tachycardia	34	(29.8%)
Alcohol	72	(63.2%)
Diabetes mellitus	13	(11.4%)
HIV	1	(0.9%)
Right lobe	84	(73.7%)
Left lobe	8	(7%)
Bilateral lobe	22	(19.3%)
Solitary	71	(62.3%)
Multiple	43	(37.7%)

Involvement of the right lobe of the liver (73.7%, n = 84) was more common compared to the left lobe (7%, n = 8) and bilateral lobe involvement (19.3%, n = 22).The majority of patients had a solitary liver abscess (62.3%, n = 71) as compared to multiple (37.7%, n = 43). Tachycardia (pulse rate >100 per minute) was found in 29.8% of the patients.

Biochemical abnormalities were compared between the solitary and multiple liver abscess (Table 2). Anaemia was present in more than half the patients and leucocytosis was observed in 75.4% of patients. Hypoglycemia ⁸ (plasma glucose concentration ≤70 mg/dl or ≤3.9 mmol/L) was present in 28 (24.6%) patients, the majority (22 patients) having a solitary liver abscess (P = 0.04, odds ratio [OR] = 2.76). All the patients had asymptomatic hypoglycaemia (plasma glucose concentration ≤70 mg/dl). Hypokalaemia was seen in 18 patients (15.8%), predominantly in patients with solitary liver abscess (P = 0.04, OR = 3.57). Similarly, raised serum alkaline phosphatase was also more common in patients with a solitary liver abscess (P = 0.05, OR=3.06). Hypoalbuminaemia was present in the majority of patients (90.4%, n = 103) while coagulopathy was present in (35.1%, n = 40). A significant number of patients (45.6%, n = 52) could be managed with the use of antibiotics only. Twenty-three (20.2%) patients underwent PNA while 35 (30.7%) underwent PCD, all successfully. Surgery was needed in only a few patients (3.5%, n = 4). The mean volume of liver abscess in PNA and PCD subgroups was 203.30 mL (range, 30–1012 mL) and 518.51 mL (range, 100–1460 mL), respectively. The mean duration of hospital stay was 12.10 ± 5.64 days, which was increased by 1.6 days in PNA and 2.4 days in PCD patients. There were only four (3.5%) fatalities. Two fatalities were due to atrial fibrillation while the two others succumbed to acute respiratory distress syndrome (ARDS); one patient had pneumonitis while other had ruptured abscess in pleura and lung leading to ARDS.

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Table 2.

Comparison of laboratory abnormalities between solitary and multiple ALA.

Parameter	Reference	Value	Solitary (n = 71)	Multiple (n = 43)	P value*
Anaemia	Hb	120 g/L	40	26	0.66
Leucocytosis	TLC	>11.0 × 109/L	52	34	0.48
Thrombocytopenia	Plt Ct	<150 × 109/L	8	9	0.16
Hypoglycaemia	RBS	≤3.88 mmol/L	22	6	0.04
AKI	Creatinine	>132.6 µmol/L	6	5	0.57
Hyponatremia	Sodium	<135 mEq/L	41	34	0.02
Hypokalaemia	Potassium	<3.5 mEq/L	15	3	0.04
Hyperbilirubinaemia	Bilirubin	>34.2 µmol/L	17	5	0.10
Raised AST	AST	>40 U/L	40	30	0.15
Raised ALT	ALT	>40 U/L	40	28	0.35
Raised ALP	ALP	>270 U/L	17	4	0.05
Hypoproteinaemia	Protein	<60 g/L	23	21	0.08
Hypoalbuminaemia	Albumin	<35 g/L	61	42	0.03
Coagulopathy	INR	≥1.5	18	22	0.005

Discussion

ALA has a spectrum of clinical presentation ranging from asymptomatic colonic infection to complicated form of disease associated with life-threatening consequences. ALA can develop at any age but most commonly presents in the younger age group with a highest incidence in the third and fourth decade of life. In our study, the mean age of presentation was 41.7 ± 13.9 years with a slight male preponderance which is consistent with other studies.^9,10 Abdominal pain (92.1%) and fever (88.6%) were the most common symptoms while tender hepatomegaly (78%) was the most common sign noted. The presence of gastrointestinal symptoms were uncommon (diarrhoea 7%, per rectal bleeding 6.1%). Alcohol (63.2%) was the most common co-morbidity associated with ALA followed by diabetes mellitus (11.4%) which was similar to other studies. ¹¹ In contrast, however, to other studies from India and elsewhere,^12,13 only one patient tested positive for HIV as its incidence is very low in our region of central India.

Ultrasound of the abdomen is the most easily available radiological investigation which can quickly diagnose ALA. The location of the abscess relates to the entry site of the parasite in the colon and its subsequent passage to the corresponding liver drainage area via the portal system.^14,15 There was a preponderance of right lobe ALA (73.7%) while bilateral lobe involvement was present in 19.3%. Globally, solitary ALA^13,16 seems more common than multiple ALA, and our findings showed no difference (solitary 62.3%, multiple 37.7%).

Some new laboratory abnormalities of significant importance, however, came to light: hypoglycaemia was present in 24.6% patients, more commonly in patients with solitary ALA. The cause of hypoglycaemia is probably the replacement of hepatocytes by the abscess cavity leading to glycogen depletion and impaired gluconeogenesis. Electrolyte imbalance especially hyponatremia was present in 65.8% of patients. Both hypoglycaemia and hyponatremia are easily correctable during hospital admission. Raised aminotransferases were noticed in approximately 60%. Elevation of aminotransferases is probably due to hepatocellular inflammation induced by parasite (trophozoites).

Hypoalbuminaemia (90.4%) was almost universal and leucocytosis (75.4%) was predominant, as past studies.^8,10 Just under half of patients could be managed either by medical treatment (45.6%) or by minimally invasive drainage techniques (49.1%); invasive surgery was recommended in only 3.5%.

Over the past two decades, percutaneous drainage techniques (PNA and PCD) have emerged as popular choices for complicated ALA depending on their size and location. In the case of uncomplicated ALA, the use of potent amoebicidal drugs was initially considered superior to PNA ¹⁷ but later studies suggested that a combined treatment strategy (antibiotics and PNA) was superior, especially for abscesses size >6 cm in diameter. It is important to drain left lobe ALA as there is danger of rupture in the pericardial sac. The initial response to treatment was quicker in the latter group though the rate of resolution after 6 months was similar. ¹⁸

The success rate of PNA is described as in the range of 79–100%.^19,20 PCD seemed to have a 100% success rate. ²¹ We used PCD for larger abscesses, hence their slightly longer hospital stay. We had a very low mortality concomitant with other studies. ²² A basic limitation of our study is that it is retrospective, and an extensive follow-up was not possible.

In conclusion, ALA is predominantly a disease of young and middle-aged alcoholic men involving a solitary site in the right liver lobe. Hypoglycaemia and hyponatremia should be corrected during the hospital stay. Minimally invasive drainage techniques play a vital role in the treatment of almost 50% of cases.