Repair of an indirect inguinal hernia is the most common procedure performed by pediatric surgeons, yet the need for contralateral exploration remains controversial. This prospective study evaluated the use of laparoscopy combined with the selective use of probing to determine the presence or absence of a contralateral patent processus vaginalis (CPPV).A consecutive series of 75 of the author's patients presenting with a unilateral inguinal hernia were studied. Laparoscopy was performed through the known hernia sac with CO2 insufflation utilizing a 4-mm 70 degrees telescope to inspect the contralateral inguinal region. A patent processus was diagnosed when an obvious opening through the internal ring was identified. In some patients this evaluation was found to be inconclusive because of the inability to determine accurately the length of the patent processus or to rule out a patent processus obscured by a veil of peritoneum. This group of patients was then evaluated selectively with a silver probe placed under direct vision through a 14-gauge intravenous catheter placed through the abdominal wall on the side in question to manipulate the peritoneum and directly measure the length of the potentially patent processus. A patent processus greater then 1.5 cm was considered positive.A total of 54 patients (72%) had a conclusive laparoscopic evaluation of the contralateral inguinal region with a CPPV clearly absent in 38 and an obvious CPPV present in 16. A total of 21 patients (28%) had inconclusive laparoscopy finding and were evaluated further with probing. The probing technique changed the determination of a CPPV in 15 patients (12 positive to negative and 3 negative to positive; P = .029, Fisher's Exact test). Probing resulted in a decrease in the overall rate of identification of a CPPV from 45% to 32%.In inconclusive cases, the addition of selective probing to the laparoscopic evaluation for a CPPV reduces the number of patent processus vaginalis found and the need for contralateral inguinal exploration.