Chronic ectopic pregnancy presenting as a suspected tubo-ovarian abscess: a diagnostic dilemma
An ectopic pregnancy (EP) occurs when the gestational sac is implanted outside of the endometrial cavity. An absolute majority of cases of ectopic pregnancies are implanted in the fallopian tube and present clinically with symptoms of amenorrhoea, lower abdominal pain and vaginal bleeding. Chronic EP (CEP) is a variant of EP, which is difficult to diagnose with variable and non-specific clinical signs and symptoms and there remains no universal agreement about the definition of CEP. Often it is a retrospective diagnosis considering the clinical presentation and intra operative findings. Serum B-HCG, which is a reliable marker in monitoring as well as establishing a diagnosis of EP, tends to remain low or negative in CEP due to sparse chorionic villi, adding further challenges to making the diagnosis. CEP often develops when the trophoblastic tissue gradually invades through the implantation site leading to repeated rupture at the site and continued minor bleeding that over time can develop into a haematocele and appear as a pelvic mass. However, the final diagnosis of CEP is often made at histology with findings of haemorrhage and blood clots, disintegration of the tubal wall, multiple minor ruptures, and areas of dense fibrosis and necrosis embedded within degenerated and/or avital chorionic villi.
CASE PRESENTATION
A para 2+2 presented to the gynaecology assessment unit with a 4-day history of severe lower abdominal pain associated with mild PV bleeding, which was presumed to be normal periods. She had had a spontaneous miscarriage 4weeks prior and her serum B-HCG levels had dropped from 700 IU/L to 400IU/L and 3 weeks postmiscarriage urine pregnancy test was negative. She had no history of similar pain, no history of dysmenorrhoea, no bowel or urinary symptoms or previous pelvic inflammatory disease or use of intrauterine contraceptive device.
On examination, there was localised tenderness in the right iliac fossa, there was no guarding or rebound tenderness, pelvic examination show a healthy looking cervix minimally smeared with altered blood, there was no cervical motion tenderness. Her blood results revealed a haemoglobin of 101g/L, a C reactive protein of 25mg/L, normal urea and electrolytes and a serum B-HCG of 3 I U/mL. Transvaginal pelvic ultrasound showed a heterogeneous mass in the right adnexa measuring 32×29×61mm, suggestive of a tuboovarian abscess/mass.
She was admitted and was started on conservative management with intravenous antibiotics and analgesia with a view for consideration of a diagnostic laparoscopy, if there was no clinical improvement. Tumour markers which were normal and an MRI pelvis showed large amounts of fluid, possible blood in the pelvis and a right adnexal structure adjacent to the uterus. She went on to have a diagnostic laparoscopy with a proceed to right salpingectomy and a peritoneal lavage. Intraoperatively, there was about 50 mL of haemoperitoneum all over the abdomen and in the pelvis, a right ampullary swelling suggestive of ectopic with an unhealthy right tube stuck to the anterior abdominal wall, the tube with the ectopic were excised and the tissue retrieved using an Endo catch retrieval bag through the 10mm suprapubic port. The uterus, right and left ovaries were all normal. Histology of the specimen showed fallopian tube containing immature chorionic villi, intermediate trophoblast, blood and fibrin, supporting a diagnosis of a CEP.
CEP is a rare and challenging diagnosis, with few cases reported in literature and often presents with similar symptoms to an EP, namely amenorrhoea, lower abdominal pain and vaginal bleeding. However, because of the protracted nature of symptoms and often negative B-HCG (Beta- Human chorionic gonadotropin) as a result of inactive or avital trophoblast in women with CEP it often poses a diagnostic dilemma. The most common presenting symptom of women with CEP is abdominal pain, followed by irregular vaginal bleeding, and fever. An ultrasonographically visible adnexal mass at the time of the initial diagnosis is usually found in about half of cases of CEP.
Source: Alao AI, et al. BMJ Case Rep 2023;16:e253396. doi:10.1136/bcr-2022-253396
