Aim Less than a dozen cases of psoas abscesses in pregnancy have been described in the literature. We reviewed the literature when treating a patient with a psoas abscess after ipsilateral double J-ureteral stent placement (in the following: “double J-stent”) due to infected hydronephrosis. Methods In January 2022, this review was searched using the Pubmed/MEDLINE database and the mesh terms “Psoas Abscess” AND “Pregnancy”. Studies were included in any language and of all years, describing a psoas abscess during pregnancy. When patients did not have a psoas abscess, the abscess occurred after pregnancy, or when there was no full text available, the article was excluded. Main results Ten case reports about patients with psoas abscesses during pregnancy were included. The classical symptomatic triad of psoas muscle abscess included lower back pain, limping and persistent fever with daily spikes. However, in most cases, not all three symptoms can be found. Especially, fever is absent in more than half of the patients. Psoas abscesses are described between 13 and 39 weeks of gestation. Primary psoas abscesses with haematogenous spread are more common during pregnancy than secondary with spread per continuitatem. In the literature, the main reasons for psoas abscess are spinal tuberculosis, drug abuse or underlying diseases such as Crohn’s disease. It is not uncommon for the definite cause to be unclear. Regarding the patient's symptoms, pyelonephritis is often considered a possible aetiology. In general, the main treatment options include antibiotic treatment and abscess drainage. There is no higher caesarean section rate, and no negative outcome for the foetus has been described. Case presentation In our patient, a 38-year-old obese Caucasian woman, who had received a left double J-stent for infected hydronephrosis at 15 weeks of gestation, we successfully treated a psoas abscess of 20 × 10 cm with a sonographically assisted abscess drainage and antibiotics. The further course of pregnancy and the elective repeat caesarean section at 38 + 0 weeks of gestation were without any problems. Double J-stent placement and laser stone lithotripsy during puerperium were performed because of recurrent urolithiasis. Conclusions Although rare, psoas abscesses can occur during pregnancy, and it has often been treated surgically in the past. A psoas abscess as a complication after infected hydronephrosis and intervention during pregnancy has never been reported in the literature. Even for obese patients, minimally invasive therapy may be a treatment option that has rarely been reported in the literature.

Aim: Less than a dozen cases of psoas abscesses in pregnancy have been described in the literature. We reviewed the literature when treating a patient with a psoas abscess after ipsilateral double J-ureteral stent placement (in the following: “double J-stent”) due to infected hydronephrosis. Methods: In January 2022, this review was searched using the Pubmed/MEDLINE database and the mesh terms “Psoas Abscess” AND “Pregnancy”. Studies were included in any language and of all years, describing a psoas abscess during pregnancy. When patients did not have a psoas abscess, the abscess occurred after pregnancy, or when there was no full text available, the article was excluded. Main Results: Ten case reports about patients with psoas abscesses during pregnancy were included. The classical symptomatic triad of psoas muscle abscess included lower back pain, limping and persistent fever with daily spikes. However, in most cases, not all three symptoms can be found. Especially, fever is absent in more than half of the patients. Psoas abscesses are described between 13 and 39 weeks of gestation. Primary psoas abscesses with haematogenous spread are more common during pregnancy than secondary with spread per continuitatem. In the literature, the main reasons for psoas abscess are spinal tuberculosis, drug abuse or underlying diseases such as Crohn’s disease. It is not uncommon for the definite cause to be unclear. Regarding the patient's symptoms, pyelonephritis is often considered a possible aetiology. In general, the main treatment options include antibiotic treatment and abscess drainage. There is no higher caesarean section rate, and no negative outcome for the fetus has been described. Case presentation: In our patient, a 38-year-old obese Caucasian woman, who had received a left double J-stent for infected hydronephrosis at 15 weeks of gestation, we successfully treated a psoas abscess of 20 x 10 cm with a sonographically assisted abscess drainage and antibiotics. The further course of pregnancy and the elective repeat caesarean section at 38 + 0 weeks of gestation were without any problems. Double J-stent placement and laser stone lithotripsy during puerperium were performed because of recurrent urolithiasis. Conclusions: Although rare, psoas abscesses can occur during pregnancy, and it has often been treated surgically in the past. A psoas abscess as a complication after infected hydronephrosis and intervention during pregnancy has never been reported in the literature. Even for obese patients, minimally invasive therapy may be a treatment option that has rarely been reported in the literature.