Anorectal Manometry and 3D High-Definition Anorectal Manometry in Pediatric Settings

Fig. 8.1

Normal RAIR. White and black arrows point rectal balloon insufflation and deflation, respectively. The balloon inflation induces an increase in the rectal pressure, shown in the figure as purple bar. Normal RAIR is seen as a drop in anal canal pressure upon rectal balloon insufflation

../images/475577_1_En_8_Chapter/475577_1_En_8_Fig2_HTML.jpg — Fig. 8.2

Absent RAIR. *White* and *black arrows* point rectal balloon insufflation and deflation, respectively. The balloon inflation induces an increase in the rectal pressure, shown in the figure as *purple bar*. The anal sphincter pressure does not decrease upon rectal balloon insufflation. RAIR is absent in several conditions including colonic aganglionosis or Hirschsprung disease

../images/475577_1_En_8_Chapter/475577_1_En_8_Fig3_HTML.jpg — Fig. 8.3

Squeeze pressure. It is elicited by asking the child to voluntarily contract the anal sphincter. It is calculated as the greatest pressure increase referred to the baseline resting pressure

../images/475577_1_En_8_Chapter/475577_1_En_8_Fig4_HTML.jpg — Fig. 8.4

Endurance squeeze. It is the length of time the child is able to maintain the anal canal pressure during a voluntary contraction. It is elicited by asking the child to voluntarily contract the anal sphincter as strongly as possible for a period of at least 15–20 s. The *white arrows* point the start and the end of the squeeze

../images/475577_1_En_8_Chapter/475577_1_En_8_Fig5_HTML.png — Fig. 8.5

Bear-down maneuver or push in dyssynergic defecation. It is carried out to evaluate anorectal and pelvic floor pressure changes during a simulated defecation. Normal defecation attempt induces a simultaneous and coordinate increase in the rectal pressure and relaxation of anal sphincters. In the figure, there is an increase in rectal pressure (*white square*) but paradoxical increase in anal pressure, consistent with the diagnose dyssynergic defecation, which is a common cause of fecal outlet obstruction in children

8.3.3 Reference Values

In pediatric age, there is a lack of uniformity in terms of protocols and equipment, and hence lack of normal reference values. Moreover, normal HRAM and 3D HRAM values have been published only for adult populations [20–23], while only few studies have been performed in children with similar methodologies. Hence, the interpretation still relies on expertise of the pediatric gastroenterologists in the field. Moreover, conventional water-perfused ARM measures are routinely used in manometry reporting despite in adult literature has shown that the values with high-resolution manometry are higher than those with water perfusion [24]. Moreover, significant variability in values might depend on gender, BMI, age, use of different protocols, and the interaction between the patient and the clinician [21, 22, 25, 26].

To date only two studies in pediatric age have been performed using HARM and 3DHARM in order to establish normative values. One study using HARM reported normal values of anorectal sphincter metrics (including resting pressure, anal canal length, and RAIR) in 180 healthy and asymptomatic newborns based on age, and segregated by preterm vs term [27]. Recently, Banasiuk et al. have published a study aimed at evaluating normal 3DHRAM values in 61 children without symptoms from the lower gastrointestinal tract [8]. Normal values in pediatric age using either low- or high-resolution manometry are summarized in Tables 8.1 and 8.2.

Table 8.1

Normal manometric values in term and preterm neonates found in pediatric studies published using either low- or high-resolution anorectal manometry (Zar-Kessler et al. [18], modified)

	Equipment (technique)	Healthy patients (n)	Ages		Anal resting pressure (mmHg)	Anal canal length (cm)	RAIR threshold volume (mL)	Patients with normal RAIR (%)	Rectal pressure (mmHg)
Kumar et al. [2]	Water-perfused LR	30	3–28 D 34–39 weeks of GA		31.07 ± 10.9	1.67 ± 0.34	9.67 ± 3.7
Benninga et al. [28]	Water-perfused LR	22	30–33 weeks PMA		32 ± 4		1.6 ± 0.3^a	92%^a	9 ± 2
Benninga et al. [28]	Water-perfused LR		33–38 weeks PMA		51 ± 4		1.9 ± 0.2	100%	11 ± 3
de Lorijn et al. [29]	Water-perfused LR	16	3–23 D 27–30 weeks PMA		24.5 ± 11.4		3.4 ± 1.6^a	81%^a	6.5 ± 4.8
Tang et al. [27]	Water-perfused HRARM	85	0.5–85 D Preterm neonates 28–36 weeks of GA	≤7 D	23.1 (19.9–26.2)	1.8 (1.7–2.0)	1.6 (1.4–1.9)
				8–30 D	27.7 (24.8–30.6)	1.9 (1.7–2.0)	2.2 (1.7–2.7)
				≥31 D^b	32.9 (29.6–36.2)	2.0 (1.7–2.3)	3.7 (2.8–4.7)
		95	1–67 D Term neonates 37–42 weeks of GA	≤7 D	28.9 (25.8–32.0)	1.9 (1.7–2.1)	2.8 (2.3–3.3)
				8–30 D	31.6 (28.9–34.3)	2.0 (1.9–2.1)	3.5 (2.9–4.0)
				≥31 D^b	39.9 (35.6–44.1)	2.3 (2.1–2.4)	4.5 (3.9–5.0)

D days of life, LR low resolution, GA gestational age, PMA postmenstrual age

^aAir insufflation: 1–5 mL of air was directly insufflated into the rectum to elicit the RAIR, instead of inflated balloon

^bIn this group healthy patients older than 1 month of life (infants) were included

Table 8.2

Normal manometric values for infants and children found in pediatric studies published using either low- or high-resolution anorectal manometry (Zar-Kessler et al. [18], modified)

	Equipment	Healthy patients (n)	Ages	Anal resting pressure (mmHg)	Anal canal length (cm)	Maximal squeeze pressure (mmHg)	RAIR threshold volume (mL)	First sensation volume (mL)	Critical volume (mL)	Rectal pressure (mmHg)
Benninga et al. [3]	Water-perfused LR	13	8–16 Y	55 ± 16		182 ± 61	18 ± 10	19 ± 12	131 ± 13
Kumar et al. [2]	Water-perfused LR	30	35 D–16 M	42.43 ± 8.9	1.86 ± 0.6		14.0 ± 9.5
Kumar et al. [2]		30	18 M–12.3 Y	43.43 ± 8.79	3.03 ± 0.52		25.0 ± 11.6
Li et al. [30]	Not mentioned	10	7–14 Y		4.0 ± 0.9			28.0 ± 11.4	117.0 ± 46.2
Sutphen et al. [31]	Water-perfused LR	27	6.5–12 Y^a	80.9 ± 24.3		141.7 ± 47.2		30.4 ± 11.9	95.6 ± 38.1	13.0 ± 13.0 (resting) 60.5 ± 22.0 (defecation)
Banasiuk et al. [8]	Solid state 3DARM	9	2–5 Y	94 (24)	2.2 (0.5)	201 (60)^b	13.3 (7.5)	34 (28.8)^c	36 (27)^c
		19	5–8 Y	86 (15)	2.4 (0.4)	206 (40)^d	11.1 (3.2)	25 (32.9)^d	37.2 (35.9)^d
		19	9–12 Y	94 (15)	2.9 (0.6)	206 (59)	13.7 (5.9)	14.7 (6.9)	36.3 (19.8)
		14	12–17 Y	96 (19)	3.1 (0.7)	229 (65)	18.6 (15.1)	22 (11.9)	55 (39.9)