الفهرس 
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Abstract
Genetically, sex is determined at fertilization, by the contribution of a Y or an X chromosome from the sperm; this contribution determines the differentiation of the primordial gonads. Thus, the presence or absence of a Y chromosome, with its testis-determining factor, primarily determines the course of sexual differentiation.
This differentiation starts by the 4th week of gestation; the XY karyotype is normally associated with male differentiation, and the XX karyotype is normally associated with female development.
A full-term male infant is expected to possess bilateral testicles that are descended complete formation of scrotal folds including midline fusion, a typical size penis (average penile length is 3.5 ± 0.4 cm, for a full term).
In contrast, a full-term female infant is expected to have bilateral separation of the labial folds, no palpable gonads, and separate urethral and vaginal openings. The average clitoral length and width for a full term infant girl born in. Is 4.0 ± 1.24 mm and 3.32 ± 0.78 mm, respectively.
Hormonal fluctuations in the neonatal period can result in changes in the genitourinary area that are concerning to parents. The genitalia of both male and female infants may appear relatively large and swollen at birth due to several factors, including exposure to hormones produced by both the mother and the fetus, bruising and swelling of the genital tissues related to birth trauma, and the natural course of development of the genitalia.
Also prematurity has great effect on the appearance of eternal genitalia and can cause unusual looking genitalia that can be mistaken with ambiguous genitalia so careful examination of the genital system at birth is mandatory to differintiate common genital variation in neonatal period from other pathological forms and this is important for reassurance and counseiling.
Hydrocele is one of Common neonatal variation in external genitalia in male newborn as a result of a fluid collection around the testicle within the tunica vaginalis and resolves around first year.
Common neonatal variation in external genitalia in female newborn are Hymen Tag, pseudomenstruation and uric acid crystal deposition.
Penile length may differ in different populations, with race and ethnicity, and may yield different normal values.
The accurate measurement of SPL is very important in children with abnormal genital development such as micropenis, buried penis and hypospadias and is essential to find out underlying endocrine disorders.
In our study we aimed at clinical assessment of external genitalia in newborn, early detection of abnormalities and awareness of the family about the importance of early intervention and followup.
This study was carried out on 400 newborn of both sex aged from one day to one month from primary health care centers and units Menoufia university hospital in a period of one year from Mars 2018 to Mars 2019.
Summary
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Inclusion criteria:
All newborn are included regardless sex and maturity.
Exclusion criteria:
Those who have multiple congenital anomalies or part of syndromes are excluded.
In our study
All newborn babies were subjected to the following after taking informed consent approved by the local ethics committee of Menoufia University:
1.Detailed history taking (perinatal history)
2.Family pedigree
3.Thorough clinical examination
4.Anthropometric measurements
5.Examination of the external genitalia:
Newborns were examined in a warm room in a comfortable temperature removing the clothes in presence of the parents and with gloved clean hands. Proper visualization was done with the infant in a supine position, legs flexed and abducted at the hips.
A. Examination of male genitalia
Scrotal examination
Examination of both Testes
Measurement of stretched penile length (MSPL)
Location of the urethral meatus
B. Examination of female genitalia
Labia (majora, minora)
Clitoris
Hymen
Vaginal introitus
Urethral orifice
6.Genetic counseling
7.Data management and statistical analysis
This study revealed that:
The current study included 400 neonates their gestational age ranged between 28 and 42 weeks with mean of 38±1.4 weeks (41.5%) of them were males, 234 (58.5%) of them were female. 36 preterm and 364 full term.
Anthropometric measures of the studied neonates showed that; Mean ±SD for weight was 3.3±0.5 kg, their length was 49.3±1.8 cm and their head circumference was 34.4±1.1 cm.