Usefulness of a mobile airwayscope with a monitor in examination of the external genitalia of a 483 g female neonate

Every neonate requires a detailed examination of the external genitalia for sex assignment. Conventional approaches for the examination in female extremely low birthweight (ELBW) neonates in the closed incubator are challenging. Under direct visual inspection from outside the closed incubator, evaluation may be insufficient, owing to the small body size. It is necessary to lift the lower limbs and buttocks to enable physicians to examine the perineum thoroughly. However, this practice is potentially against the minimal handling protocol for ELBW neonates. In a previous study, an endoscope-assisted technique helped physicians to identify the urethral meatus in a male ELBW neonate with hypospadias.¹ It remains unknown whether this endoscope-assisted technique can be applied to examinations of perineum of female ELBW neonates. Here, using a mobile airwayscope with a monitor, we examined the external genitalia in a 483 g female neonate.

The patient was born via vaginal delivery to a healthy mother at 22 weeks and 3 days of gestation due to impending preterm labor caused by cervical incompetence. The birthweight was 483 g (−0.78 SD). The patient was intubated and on mechanical ventilation in a closed incubator. The external genitalia of the patient were too small for adequate examination from outside the incubator (Figure 1a). On postnatal day 5, using a flexible mobile airwayscope, we examined the external genitalia of the patient remaining in the incubator for 7 min (Figure 1b). The mobile airwayscope (Olympus MAF-DM2, Olympus Corporation, Tokyo, Japan) had the following specifications: (i) a monitor allowing the inspector to manipulate the scope safely and effectively; (ii) a picture or video recording function; (iii) light emitting diode at the tip to illuminate objects; (iv) a 3.1 mm tip diameter, and (v) a length of 600 mm. During the mobile airwayscope-assisted examination, we identified a vaginal vestibule-like structure with no swelling of the labioscrotal folds; however, we could not identify the urethral meatus (Figure 1c). By retrospectively evaluating still images, the anogenital ratio and clitoral width were estimated to be 0.45, and 5.8 mm, respectively (Figure 1c,d). After the examination, the patient did not develop any fluctuations in vital signs or infectious diseases. Since the patient was not in good condition, abdominal ultrasonography for internal genitalia was not performed. We extracted DNA from the umbilical cords. A polymerase chain reaction revealed the absence of SRY (data not shown). Our medical differences of sex development team discussed the clinical information and results of the examinations, including images of the external genitalia. We shared the discussion and limitations with the parents, namely no reference ranges or normal findings in ELBW neonates' external genitalia. On postnatal day 11, the parents assigned and registered their baby's sex as female.

FIGURE 1

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Inspection of the external genitalia of the patient. (a) View from outside of the closed incubator. The external genitalia of the patient cannot be examined sufficiently from outside the incubator. (b) Examination scene. A mobile airwayscope is placed in front of the external genitalia. (c) Image of the patient's perineum. (d) Estimation of clitoral width by referring to the scale.

We comprehensively examined the external genitalia in the 483 g female neonate using a mobile airwayscope with no adverse events. Using a mobile airwayscope, we overcame the two limitations of the conventional approach in our patient. Inspection of the external genitalia in female ELBW neonates may be insufficient, owing to the small size of neonates. Identification of the urethral meatus and vaginal vestibule is difficult. The mobile airwayscope enables us to obtain magnified image of the external genitalia at arbitrary angles. This allowed detailed observation of the perineum in a normal posture. Furthermore, by retrospectively evaluating still images, we estimated the anogenital ratio and clitoral size accurately. Accurate measurement with a 1 mm scale ruler is impossible because each part of the external genitalia in female ELBW neonates is small.

Using the mobile airwayscope-assisted examination of the patient, the anogenital ratio and clitoral width were estimated to be 0.45, and 5.8 mm, respectively. However, external genitalia findings obtained by our method alone may not be sufficient for sex assignment in ELBW neonates. This is due to the lack of reference data for the structures of the external genitalia of ELBW neonates. The appearance of external genitalia in female ELBW neonates varies widely between individuals, particularly the size of the clitoris.^{2, 3} To evaluate the external genitalia of neonates with such wide variations precisely, we must establish the references that adjust for factors such as sex, weight, and gestational age. When we evaluate the external genitalia of term neonates using our method, we cannot apply the reference data of neonates obtained by conventional measuring methods. Using the conventional measuring method, the penis length is measured in a manually stretched position,⁴ whereas using our method, the penis length is measured on the image in a flaccid position.

In our patient, the identification of a vaginal vestibule-like structure and the absence of SRY assisted physicians and parents in assigning the baby's sex as female. We suppose that non-invasive genetic testing using umbilical cord samples provides valuable supplementary information for sex assignment.^{1, 5}

In summary, we reported a female ELBW infant whose external genitalia were safely and effectively examined using a mobile airwayscope with a monitor.