The study encompassed 37 patients diagnosed with the MIP hypospadias variant between 2008 and 2022. Six patients were excluded as they did not receive or refused telephone satisfaction surveys, leaving 31 patients with complete clinical data who were contacted for telephone follow-up. This resulted in a 16.2% rate of lost follow-up. Among the 31 MIP patients, the average age was 92.1 ± 40.7 months, with a median follow-up duration of 49.0 [21.0–82.2] months.

Among 31 MIP patients, the artificial erection test during surgery revealed that 21 (67.7%) presented with ventral curvature, with no instances of dorsal curvature observed. As detailed in Table 1, the patients were categorized into two groups: those with curvature and those without. The average age in the curvature group was 80.4 ± 41.6 months, markedly different from the 117.0 ± 26.0 months in the no curvature group (P < 0.01). Similarly, a significant contrast was found in median weights between the groups: 22.7 [15.8–35.0] kg in the curvature group versus 45.0 [32.0–46.0] kg in the no curvature group (P = 0.02). In the curvature group, the urethral openings were located as follows: 14 in the glans, 6 in the coronal sulcus, and 1 in the distal penis. In the no curvature group, there were 4 in the glans, 6 in the coronal sulcus, and none in the distal penis, with no statistically significant difference (P = 0.23). Following degloving, 12 cases required dorsal plication to correct persistent curvature, while one case involved urethral plate transection due to severe curvature. For further details, refer to Fig. 1.

Clinical characteristics and treatment of 31 MIP patients

Post-operative complications were observed in 6 children (19.4%), though none required reoperation. The complications included 2 cases of adherent prepuce, 2 instances of urethral strictures, 1 case of a small urethral diverticulum that did not require surgical intervention, and 1 case of glans dehiscence caused by accidental catheter removal with excessive force by the patient. Among the urethral strictures, one case was identified after catheter removal and successfully treated by reinserting the catheter, followed by a delayed removal 2 months post-surgery. In the other urethral stricture case, parents reported a thin stream of urine, but the child did not face any difficulty in urination, and the stream’s thickness remained stable up to the writing of this manuscript. The patient is currently under continuous observation, and surgical intervention has been deemed unnecessary at this time.

As shown in Table 2, we divided patients into no complication group (N = 25) and complication group (N = 6). The only statistical difference between the two groups was the position of the urethral opening and satisfaction rate (p < 0.05).

Regarding satisfaction with surgical outcomes, 85.7% of parents and patients with penile curvature expressed satisfaction, compared to 90.0% in those without curvature. As illustrated in Fig. 2, of the 21 children identified with curvature, 13 underwent urethroplasty, achieving a satisfaction rate of 76.9%, while the 8 who did not undergo the procedure reported 100% satisfaction. No significant statistical difference was observed between them (P = 0.26). Twenty-three cases of abnormal urethral openings were identified intraoperatively, while 8 cases were detected preoperatively. Among the intraoperatively diagnosed cases, 87% were satisfied with the outcomes, compared to 87.5% in the preoperatively diagnosed group, with no statistically significant difference between the two groups (P = 1.00).