Renal dysplasia is a rare entity. Its incidence is 2.6 cases per year [4]. For others, it is 1/4300 births [2]. We observed 2 cases in 7 years out of more than 10,000 obstetric ultrasounds performed during the 2nd and 3rd trimesters. It is generally unilateral, affecting the left side in 75% of cases [4]. Bilateral forms are rarer, representing 1/4 of cases, and are usually fatal [5]. However, in the study by Hekmat Chaara et al. [4], it was bilateral in 61% of cases, which corroborates our case. Renal dysplasia most often affects boys in 60% of cases, with a sex ratio of 1.48 [6], according to most authors [4][6]. Hekmat Chaara et al. [4] reported a male predominance of 71% and a sex ratio of 2.6/1. Our cases were female, as in the case of Faye Dieme M.E [1]. This could be explained by the small number of cases in our series.

It is made by ultrasound in almost all cases (94%) prenatally [4][7] during the morphological examination between 20 and 22 weeks of gestation. The sensitivity of ultrasound varies between 80 and 100% with a false-positive rate of approximately 2% [8]. Classically, ultrasound reveals anechoic intrarenal cysts, often large, of unequal size, varying in number, with a chaotic distribution within the kidney, and non-communicating. The residual renal parenchyma is echogenic, completely remodeled and fibrous, thinned, and sometimes unidentifiable, which explains the non-functional nature of the affected kidney. Color Doppler ultrasound shows the absence of parenchymal vascularization. The discovery of Renal Cell Carcinoma (RCC) should prompt a careful search for an associated anomaly. Some studies have reported extrarenal malformations associated with multicystic renal dysplasia such as esophageal or duodenal atresia, meningocele or heart disease [4]. In our setting, prenatal diagnosis was delayed, occurring between 36 and 38 weeks of gestation, which limited the search for certain associated malformations. However, we did observe meningoencephalocele in both cases, which is consistent with the literature. This diagnostic delay was due to the fact that the patients were seen late, and a lack of resources was the primary reason. We also noted well-developed supernumerary fingers and toes in one case after birth, which had not been seen prenatally. However, if second-trimester ultrasounds had been performed, all these malformations could have been visualized, hence the importance of morphological ultrasound. Chaara et al. [4] noted brain malformations in 17% of cases, followed by cardiac involvement (11%) and facial and neck malformations (also 11%). The amount of amniotic fluid should also be assessed [4]. Oligohydramnios is common in bilateral forms. In our case, anhydramnios was noted in both cases, which may indicate bilateral renal insufficiency, worsening the prognosis. This condition differs from polycystic kidney disease in several important ways. First, it is generally unilateral—affecting only one kidney in 95% of cases [9]. The cysts are non-communicating, and the affected kidney does not function at all, unlike polycystic kidney disease where the kidney may be functional, but this renal function gradually declines [10].

Monitoring: Once the diagnosis is made, prenatal ultrasound monitoring is necessary to:

—Assess the progression of polycystic kidney disease, which may be stable, regress, or progress during fetal life;

—Evaluate the function and morphology of the contralateral kidney, if it is unilateral, to establish a prognosis;

—Monitor for the appearance of new renal or extra-renal abnormalities;

—Quantify amniotic fluid;

—Although the monitoring schedule is not well codified in the literature. In the series by Hekmat Chaara et al. [4], monitoring was based on repeated obstetric ultrasounds performed monthly to bimonthly to look for signs of worsening renal function. According to studies, most DRMKs tend to involute and decrease in size prenatally, either completely or partially [11]. In our case, the prenatal diagnosis was late, and this monitoring was punctuated by a fetal death in utero at one week.

The literature reports a poor prognosis for the bilateral form, describing it as lethal [1][4], which is consistent with our observation. Hekmat Chaara et al. [4] reported two cases of bilateral DRMK that survived postpartum in a series of 18 cases.