NATIONAL BOARD OF EXAMINATIONS
NEW DELHI
THESIS PROTOCOL
TOPIC
Determination of Normative values of stretched penile length in
apparently healthy term newborn in Raipur, Chhattisgarh : a
cross-sectional prospective study.
NAME OF THE CANDIDATE: DR. GIRISH KUMAR PAINKARA
DATE OF JOINING: 29/06/2020
HOSPITAL/INSTITUTE: EKTA INSTITUTE OF CHILD HEALTH,
RAIPUR, (C.G)
GUIDE: DR INDER K NATHANI (MD - PAEDIATRIC)
EKTA INSTITUTE OF CHILD HEALTH, RAIPUR (C.G)
Introduction
One of the important concerns in neonates’ physical examination is the genital
examination, especially penile size that is considered an important representation
of hypothalamic or pituitary abnormality (hypogonadotropic hypogonadism);
due to the role of androgen exposure in fetal sex development, disorders in
genital system may be a sign of disorders of sex development (DSDs) (1). Thus,
penile measurement contributes to the diagnosis of the underlying genetic or
endocrine disorders (2). In addition to diagnosis of hypothalamic and pituitary
defects, measurement of PL is important in procedures, such as circumcision, as
well (3).
Micropenis is defined as a small penis, without epispadias or hypospadias, 2.5
SDs below the mean PL (4). Likewise, an SPL >2.5 SD is considered as a macropenis
[2, 3].Pure micropenis, not associated with DSDs, benefit from early
intervention, especially in mini puberty stage of below 6 months of age, when
low dose testosterone can improve the penile length significantly (1, 5).
Micropenis is an important sign in neonates, since it may be the only clue to
the diagnosis of hypopituitarism, a potentially lethal but treatable condition [6]. It
may also raise the clinical suspicion concerning the possibility of associated
hypoglycemia, a life-threatening metabolic emergency associated with
hypopituitarism or isolated growth hormone deficiency [7]. Micropenis may also
reflect an impairment specific to the hypothalamic pituitary-gonadal axis,
including isolated hypogonadism, poorly functioning, dysgenetic testicular tissue
with malignant potential or partial androgen insensitivity [6, 7]. Early diagnosis of
micropenis is important, because it allows for various treatment options to be
implemented early [8].
Conversely, a possibly large penis with hyperpigmentation of the scrotum
alerts the physician to the possibility of congenital adrenal hyperplasia (CAH), a
condition that can be fatal if not identified [9]. This is especially crucial in resource
limited settings where newborn screening for CAH is not routinely done, as
newborn males with CAH usually don’t have other signs of androgen excess and
often die undiagnosed from salt wasting crisis [10]. Macropenis has also been
associated with rare syndromes like auriculo-condylar syndrome and caudal
dysplasia sequence [9]. Genital anthropometric measurements also help to avoid
unwarranted investigations.
Normative genital anthropometric data for healthy newborns exist and were
mainly derived from Caucasian and Asian infants [11,12, 13–15]. However, this
may not be applicable to African infants. Some studies have even demonstrated
significant differences in the same ethnic group with the passage of time and
improvement in national economic conditions [16]. Recent studies from various
parts of the world have aimed at establishing genital anthropometric norms
representing their own populations [17–21]
LITERATURE REVIEW
Penis
The penis is a phenotypic sex organ of the male.It is pendulous,
suspending from the front and sides of the pubic arch, and contains the
greater part of the urethra.It functions in part in urinary expulsion and
reproduction.
Development of testes in a male embryo begins around 6-7 weeks of
gestation, from the genital tubercle. Differentiation of sertoli cells in an
embryo commences around 6-7 weeks of gestation and Leydig cells are
visualized by 11 weeks of gestation [22]. Sertoli cells begin to secrete Anti
Mullerian Hormone around the 8th week of gestation and Leydig cells start
secreting Testosterone around 11th to 12th weeks of gestation [22].
Testosterone reaches the genital tubercle where it is converted to
dihydrotestosterone(DHT)by 5α reductase enzyme. DHT acting through the
androgen receptor on the tubercle and genital fold causes the final
differentiation of these structures into penis and scrotum respectively.[22]
Penile length
Epidemiologic studies of penile length-
Ting and Wu[23] in 2009 conducted a study on term newborn males in a
multiracial Malaysia. The study involved 105 Malays, 129 Chinese and 16
Indians and the mean SPLs for Malay as well as Chinese infants were
reported as 3.5cm ± 0.4cm, and that of Indians was 3.75 ± 0.4cm.It was also
observed that the Indian babies out of the three ethnic groups had the
longest stretched penile length.
There is paucity of information from African countries, which leaves little or
virtually no data for comparison. However, in 2010, Jarret et al[24] in
Ibadan, Nigeria studied the SPLs of 264 male neonates within 72 hours of
life and reported a mean SPL of 3.4 ± 0.5cm. The study was a very good
attempt but cannot serve as a true representative of the entire ethnic
groups in Nigeria as the majority of the subjects were from the Yoruba
ethnic group.
Birth Weight and Body Length
There have been conflicting results with regard to the relationship between
penile length and growth parameters of birth weight and body length.
Assawabumrungkul and Pichetsin[25] documented a weak but significant
positive correlation between penile length, birth weight and body length. A
potential explanation for a positive link between penile length with birth
weight and body length is that the development of penis, body length and
head circumference in the intrauterine life may be under the control of the
same growth factors.
Gestational Age:
The penis after developing at nine weeks of gestation, continues to increase
in length in utero until birth and afterwards. Assawabumrungkul and
Pichetsin[25] documented a positive correlation between the penile length at
birth and gestational age in Thailand.
AIM AND OBJECTIVES
Aim:
The aim is to determine the normative values of stretched penile
length in apparently healthy term newborn.
Specific Objectives:
The specific objectives are to:
1. Establish normative values of stretched penile length of apparently
healthy term newborn males.
2. Determine the correlation between stretched penile length and
birth weight , gestation age and body length.
SUBJECTS AND METHODS
Study Location
Tripathi and Jubesta Hospital, Raipur(C. G.)
Study design
The study was hospital based, cross-sectional and descriptive. Subjects were
enrolled consecutively within the first 72 hours of life.
Study Period
September 2020 – August 2021
Subjects
Enrolled subjects for the study were consecutive apparently healthy term
male neonates with appropriate weight, delivered in these hospitals within the
first 72 hours of life during the period of study.
Definition of terms
A term baby is one delivered between 37 completed weeks to
42 weeks of gestation. While, an apparently healthy baby is a baby who
appears to be well.
Exclusion Criteria
1. Neonates with ambiguous genitalia or suspected endocrinological
disorders
2. Babies with undescended testes and hydrocele.
3. Babies with dysmorphism or multiple congenital abnormalities
4. Neonates less than 2.5kg and more than 4.0kg
5. Neonates of non-consenting mothers.
Method of data collection
Ethical approval to conduct the study was obtained from the ethical committee
of Ekta Institute of Child Health, Raipur. Written Permissions were also from
Tripathi and Jubesta Hospital. Informed written consent was obtained from the
parent/guardian of each subject after delivery. Details of the study were
explained to the parents and only those who gave consent were included in the
study.
A complete neonatal examination was performed by the principal investigator
and the anthropometric measurements were obtained. Weight was measured
with a digital weighing scale and length was measured with an infantometer
[26].
Stretched penile length was measured from base of the penis from pubic
symphysis to the tip of the glans. Pubic fat pad was maximally depressed
when taking the measurement. Tip of the glans was identified by palpation.
Measurements were taken with a wooden spatula, which was kept at right
angles to the symphysis pubis and the penis was stretched gently to its
maximum resistance and measurements were taken along the dorsal aspect
of the penis. Two measurements were taken by the principal investigator to
nearest millimetre and the mean was calculated [26,27].
Gestational maturity was calculated from the first date of last regular
menstruation or by the dating scan done at 11 to 16 weeks of gestation.
Data was gathered during hospital stay following the delivery after
obtaining informed, written consent.
Method of data analysis
Mean penile length and statistically significant difference of penile length
(SD) values were calculated. In analysis of data mean penile length, period of
gestation, birth weight and length were considered. Continuous variables
were expressed as mean +/- 2 SD.
The sample size was calculated using the formula given below (U
Anuruddhika Kollurage et al) (2019)
Sample size n = Z2 (1- ⍺ /2)* s2/d2
Z = Critical value of specified confidence level = 1.96 (95% confidence
interval).
S=Estimated standard deviation of the measure being investigated (used an
estimate of 0.49 cm from the Tamil Nadu study).
d = Absolute precision = 0.05cm
N = (1.96) 2 0.492 / 0.052 = 369
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RESEARCH PROFORMA
SECTION 1: BIODATA OF BABY
1. Name ___________________________________________
2. Serial number_______________
3. Date of enrolment____________
4. Hospital No________________
5. Date of birth ________________
6. Age _______________(hrs)
7.Sex______________________
8. Address______________________________________________
Gestational age from LMP: -----------------------------------------in weeks
SECTION 2: EXAMINATION
Vital signs
Temperature (°C)
Pulse rate(beats/min)
Respiratory Rate(breaths/min)
Anthropometry
Weight(kg)
Length(cm)
Examination of the Genitalia
Normal appearance- Yes / No
1st Measurement 2nd Measurement Mean
Stretched penile
length (cm)
