Symptomatic urinary retention and recurrent urinary tract infections in pregnancy are frequent, especially in late pregnancy.
Many patients have sonographic evidence of hydronephrosis at the end of their pregnancy (right > left). [10] Both hormonal and mechanical factors cause this. In the case of kidney stones, these often resolve spontaneously, which is why conservative treatment such as analgesia and sufficient hydration should be the first-line treatment in the case of suspected or imaging-confirmed urolithiasis and symptomatic urinary retention. One problem during pregnancy is the non-availability of the standard urolithiasis diagnostic (low-dose native CT). The available options (MRI, ultrasound) lack sensitivity in detecting ureteral calculi. Measuring the kidney resistive index via pulsed-wave ultrasonography is a well-validated tool for evaluating obstructive ureteral disorders and may be utilised for this situation. If conservative therapy is not successful or there is an indication for immediate intervention, such as infected hydronephrosis, temporary or permanent urinary diversions should be discussed. The double J-stent is an option for temporary urinary diversion in hydronephrosis, but must be changed in 3-12 monthly intervals and therefore does not represent a permanent therapy.
Double J-stents are an effective and safe option for treating analgesia-refractory hydronephrosis in pregnancy, with rare complications. However, since the usual x-ray guidance and contrast enhancement imaging of the urinary tract by retrograde ureteropyelography cannot be used during placement, less safe ultrasound-guided positioning must be performed. Due to the possible post-interventional pain, urinary tract infections, the discomfort of the stent, and the risk of preterm labor, they are not necessarily superior to conservative therapy with analgesia. [10] A percutaneous nephrostomy is an alternative to the double J-stent but is also associated with a significant impairment of quality of life due to external urine drainage and requires change at 4-6 weekly intervals. If there is no infectious situation, diagnostic and, if necessary, therapeutic ureterorenoscopy is possible if a ureteral stone is suspected during pregnancy. [11]
In our patient, there was no evidence of a persistent ureteral stone at the time of treatment in our hospital due to the absence of indirect signs such as hydronephrosis. Consequently, further manipulation, such as repeat double J-stent insertion, percutaneous nephrostomy, or ureterorenoscopy, was not indicated.
Psoas abscesses can be divided into primary and secondary psoas abscesses: in primary abscesses, pathogenic germs spread along blood or lymph vessels, whereas in secondary psoas abscesses, the abscess spreads per continuitatem. [2]
Hermann Mynter first described psoas abscesses in 1881 with the triad of back pain, fever, and conspicuous gait. Subsequent studies showed that not all three symptoms are present in all cases. Staphylococcus aureus, Escherichia coli, or Mycobacterium tuberculosis should be mentioned as the main pathogenic germs. [12] Primary psoas abscesses are more likely in younger patients (men > women). In contrast, older patients with underlying diseases such as chronic inflammatory bowel diseases are more likely to have secondary psoas abscesses. [6]
Psoas abscesses in pregnancy are very rare. There are some case reports of psoas abscesses after vaginal delivery, caesarean section and abortion curettage, but only a few cases of psoas abscesses during pregnancy (figure 4).
Psoas abscesses occur more frequently in the second and third trimesters but have been reported from 13 and 39 weeks of gestation. The high divergence of clinical symptoms can be explained by the particular location of the psoas muscle during pregnancy. Thus, back pain, pain during hip movement, an acute abdomen, fever and elevated CRP and WBC are described. However, they can be absent in some cases. It is not uncommon for the symptoms to be interpreted as pregnancy-related and only further clarified after delivery if they persist. [9] However, misinterpreting the patients' symptoms can lead to labor induction if the symptoms are interpreted as pregnancy-related. [9]
It is essential to mention that a psoas abscess is often diagnosed after delivery, especially in the later weeks of gestation. [5, 8, 9] Especially when symptoms persist postpartum, the initial diagnosis should be re-evaluated, and a more unlikely diagnosis should be considered. This also explains why patients are often misdiagnosed, and vertebral disc affection or pregnancy-related back pain is viewed more often. [8]
Regarding the literature for tubo-ovarian or other abdominal abscesses, percutaneous drainages have been described as a safe and effective therapeutic option during pregnancy. [13, 14]
Currently, no case report in the literature describes an association between a double J-stent and a consecutive psoas abscess in pregnancy. In general, several possibilities come into question as the cause of the psoas abscess in our case report.
From a urologic perspective, a fornix rupture or pyelonephritis are possible causes of the psoas abscess. Given the unavailability of retrograde ureteropyelography, fornix rupture or ureteral perforation could easily be missed during the externally performed double J-stent insertion. Although urinoma was excluded at the time of the patient's presentation in our hospital, the occurrence of a urinoma during double J-stent insertion, which later became superinfected, cannot be ruled out.
It is recommended to consider a rarer differential diagnosis if symptoms persist after double-J placement, especially if abnormal laboratory parameters are present. Sonography offers a good diagnostic option even in obese patients. If the findings are unclear, they can be supplemented by MRI. In the end, sonography and MRI examinations were able to determine the exact diagnosis and extent of the psoas abscess in our case.
The microbiological examination for pathogenic germs revealed Prevotella bivia; no other underlying diseases or intravenous drug abuse were present. Apart from obesity, there were no other risk factors, such as diabetes or immune disorder. Despite the accidental dislocation of the drainage, the following course of the pregnancy was uneventful, and the delivery could be scheduled full-term.
A new double J-stent insertion was not performed since, in the absence of hydronephrosis, there was no clear evidence of persistent urolithiasis, and the patient did not tolerate the previous double J-stent.
Since there was a re-appearance of symptoms with evidence of urolithiasis after birth, it can be assumed that this was also the cause of the initial complaints during pregnancy.