SAA, Splenic artery aneurysm; G6P3M1T1, Gravida 6 Para 3, 1 miscarriage, 1 termination; BIBA, Brought in by ambulance; LUQ, Left upper quadrant; PV, Per vaginal; SBP, Systolic blood pressure; FAST, Focussed assessment with sonography for trauma; ROTEM, Rotational thomboelastometry; QID, quarter in die/four times each day

Splenic artery aneurysm (SAA) is a rare diagnosis. Its high mortality and typically delayed diagnosis make it a surgical diagnosis not to be missed. While rare during pregnancy, rupture of a splenic artery aneurysm carries a maternal morbidity of 75% and neonatal mortality approaching 95% ¹ . Within Australia recently there have been two prominent coroners’ reports originating from South Australia ² and Victoria ³ . While both coronial inquests recognised the disease’s rarity, it was commented that the high morbidity and mortality associated with the condition mandate a high clinical suspicion in the presentation of acute abdomen during pregnancy ^{2, 3} .

While the most common visceral aneurysm, splenic artery aneurysm is infrequently encountered. Within women of childbearing age it occurs in less than 0.1% of the population ⁴ , although true prevalence may be unknown, with many being asymptomatic ⁵ . It has a 4:1 female to male prevalence, and is typically seen at the 6 ^th decade of life ^{4– 6} . The risk factors include multiparity, angiodysplasia, atherosclerosis, polyarteritis nodosa, cirrhosis, portal hypertension and connective tissue disorders especially α1 anti-trypsin deficiency ^{4– 6} . A five-year retrospective study conducted by vascular surgeons in Dallas, Texas, at one of the largest obstetric hospitals within the USA found no diagnoses of SAA for 67,000 births, with only 35 diagnosed cases during that time, none whom were pregnant ⁴ . 89% of female patients diagnosed had previously been pregnant however, with multiparity an increased risk factor ⁴ .

The state of pregnancy is a physiological and hormonal risk factor for developing SAA. Tremble and Hill’s classic proposal ⁷ for the two causes of splenic aneurysm development, being initial weakness of the arterial wall compounded by increased systemic blood pressure, may be applied. During pregnancy, the hormones oestrogen, progresterone and relaxin cause weakness within the vessel wall ^{8, 9} . Histologically this is described as subendothelial thickening, internal lamina fragmentation, medial myelodysplasia ^{8, 9} and increased acid glycosaminoglycans within the subintimal and medial layers ¹⁰ . While the wall is weakened it is vulnerable to the increased pressures associated with the increased cardiac output, circulating volume and portal hypertension associated with the gravid state ⁸ . Aortic aneurysm, cerebral aneurysm and ovarian aneurysm have also been noted within the literature to be associated with pregnancy and multiparity ⁵ .

Splenic artery aneurysm may present incidentally during the screening ultrasounds of modern antenatal care, or with rupture ^{5, 8, 9} . The latter is classically described as a presentation of left upper quadrant pain, potentially with Kehr’s sign ¹¹ (pain radiating to left shoulder tip) with initial instability, a quiescent phase of bleeding into the lesser sac before further collapse. This double rupture phenomenon is only described in 20–30% of cases ⁵ but is important clinically as it may provide a false reassurance to treating staff. The typical size of an aneurysm at rupture is typically above 2.5cm, although ruptures of aneurysms 0.5cm in size have been described. This makes the discovery of the incidental splenic artery aneurysm during antenatal scans problematic, particularly for those under 2cm in size. The diagnosis even at rupture can be a challenge, differentials which can present similarly including pulmonary embolus, amniotic embolism and placental abruption; due to the general instability of the presenting patient imaging may be a guide to treatment but should not interrupt prompt resuscitation. Many descriptions within the literature describe confirmation of the diagnosis at laparotomy and emergency caesarean section.

While a rare presentation, rupture of a splenic artery aneurysm represents a life-threatening event for the patient and within an obstetric setting, her pregnancy. Prompt diagnosis and resuscitation in this case allowed for further evaluation with further imaging. The fact that the patient remained haemodynamically stable also allowed for the option for interventional radiological coiling. Considerations which were considered by the treating team were the risk to the foetus from radiation and contrast, combined with the potential delay of surgery in the event of a failed embolisation. The option of laparoscopic evaluation and potential progression to splenectomy was considered. This was to be the next approach in the event of a failed embolisation.

Embolisation of the spleen, while potentially less physiologically stressful than surgical intervention ⁸ is not without risk of complication ¹ . Potential risks included migration of the coil, distal infarction, abscess formation and further aneurysm rupture ^{1, 5} . The decision to embolise also needs to consider the status of the patient, anatomical location of the lesion and availability of interventional radiology. In the event of instability, prompt surgical intervention, typically through caesarean laparotomy or laparoscopy with ligation of the splenic artery and splenectomy is usually the recommended action.

The mainstay treatment of SAA outside pregnancy is radiological coiling ^{5, 8} . Introduction of coiling has drastically improved the morbidity and mortality of treatment of visceral aneurysms. Elective treatment should anticipate pregnancy in women of reproductive age with the criteria for intervention typically as a diameter >1cm ⁵. Consideration of radiological coiling anticipates the anatomical location of the aneurysm with the goal of spleen preservation, which may not be possible with aneurysms affecting the splenic hilum. The discovery of a splenic artery aneurysm incidentally during pregnancy is worth considering. Typically, embolisation is recommend above 2cm ¹⁰, with intervention ideally occurring in the 2 ^nd trimester, both to minimise harm to the foetus and reduce the risk of rupture, the majority of ruptures being described in the 3 ^rd trimester.

All data underlying the results are available as part of the article and no additional source data are required.

Written informed consent for publication of their clinical details was obtained from the patient.